“…Because of their role as tumor suppressors, the members of the two families of CDK inhibitors, the INK4 (p16, p15, p18 and p19) and the CIP/KIP (p21, p27 and p57) are often found in a silenced state in tumors of many different origins (Damo, Snyder, and Franklin 2005;); however, recent evidence in pancreatic and lung tumors shows up-regulation, rather than repression of p18 (Cdkn2c) and argues against a pure tumor suppressor role for this gene (Joshi et al, 2007;Lindberg, Akerstrom, and Westin, 2007;Pei et al, 2007), whereas p19/ARF (Cdkn2d) is almost exclusively repressed in tumors (Lowe and Sherr, 2003;Canepa et al, 2007). Our results are consistent with those findings, showing increased expression of Cdkn2c in both RB-positive and RB-negative tumors, and decreased expression of Cdkn2d in RB-positive but not in RB-negative tumors.…”